There are over 160 species in the genus Acer. However for bonsai purposes only 4 sections and their sub divisions are generally used for bonsai.
The majority of the maples (acers) that we are familiar with come originally from Japan, China and Korea, with the exception of Acer campestre (field maple), the origins of which come from Europe. The leaves of all varieties are deciduous and diacetate.
The leaves in most species are palmate, veined and lobed, with 3 to 9 (rarely to 13) veins each leading to a lobe, one of which is central or apical. The leaves resemble a hand with, in most cases, five pointed lobes – ‘Palma’ being the Latin for ‘palm of hand’.
The bark of younger trees is normally green or reddish-green and turns light grey or greyish-brown as it ages. The new shoots in spring can be yellow, orange or even bright red, and their red autumn foliage is very attractive.
They are extremely popular as bonsai and imported in vast numbers from Japan.
CULTIVARS - frequently used as bonsai
- Acer buergerianum (Trident maple)
- Acer palmatum ‘Shin-deshojo’
- Acer palmatum ‘Kiyohime’
- Acer palmatum ‘Seigen’
- Acer campestre (Field maple)
- Acer pseudoplatanus (sycamore)
GROWING AND CARE
- Maples prefer a sunny, airy position, but need some shade on very hot days. They are frost hardy, but should be protected from heavy frost and intense long-term freezing.
- Water maples regularly throughout the growing season. When they have dropped their leaves, this can be reduced to a bare minimum as they are not photosynthesising.
- Repot every one or two years, using a well-drained soil mixture. Prune the roots thoroughly – the pot will fill with roots quite quickly.
- Wire only when in leaf as twigs with less sap in them during winter are very prone to snapping.
- Shoots and twigs can be trimmed all year round.
- Regularly cut new growth back to one or two pairs of leaves on each twig. Prune strong branches only in autumn to prevent bleeding. Apply cut paste to the wounds as maples are prone to fungal infections.
- Similarly feeding should be fortnightly throughout the growing season.
- Maples are subject to aphid infestation, both greenfly and blackfly, so treat regularly with an insecticide.
- Poor autumn colour or purple-leaved varieties turning green may suggest a lack of light, such as being in a very shady spot
- Japanese maples can be very prone to leaf scorch in windy or excessively sunny positions, particularly those with fine-cut leaves. Young leaves can also be caught by frost so protect with horticultural fleece when cold nights are forecast.